Ten Gigabit Ethernet, as defined by the Institute of Electrical and Electronics Engineers (IEEE) 802.3 standard, is designed to transmit Ethernet frames at a rate of 10 gigabits per second. Ten Gigabit Ethernet utilizes physical layer (PHY) entities such as 10GBASE-T. A 10GBASE-T PHY entity is coupled to an IEEE 802.3 Media Access Control (MAC) sublayer through a 10 Gigabit Media Independent Interface (XGMII).
In operation, a conventional 10GBASE-T PHY entity receives eight XGMII data octets provided by two consecutive transfers on the XGMII. The eight XGMII data octets are grouped into 64-bit blocks. The conventional 10GBASE-T PHY entity then encodes each group of eight XGMII data octets, along with data/control indications, into a 65-bit block via a 64b/65b encoding scheme. The resultant 65-bit blocks are scrambled and aggregated into a group of 50 65-bit blocks. The conventional 10GBASE-T PHY then adds 8 cyclic redundancy check (CRC) bits to the group of 50 65-bit blocks to yield a CRC-checked payload of 50×65+8=3258 bits. An auxiliary channel bit is added to the payload to yield a block of 3259 bits.
The conventional 10GBASE-T PHY entity is designed to protect only certain bits in the payload with error correction encoding. The 3259 bits are divided into i) 1723 bits and ii) 3×512=1536 bits. The conventional 10GBASE-T PHY entity encodes the 1723 bits using a low-density parity-check code (LDPC) encoder, which adds 325 LDPC parity bits to the 1723 bits to form an LDPC codeword of 2048 coded bits (represented by LDPC (1723, 2048)). However, the 3×512=1536 bits, which includes the auxiliary channel bit, remain uncoded. The conventional 10GBASE-T PHY entity arranges the 1536=3×512 uncoded bits and the 2048=4×512 coded bits (3854 total bits) in a frame of 512 7-bit labels, where each 7-bit label contains 3 uncoded bits and 4 coded bits. The conventional 10GBASE-T PHY entity then maps the 512 7-bit labels into 512 two-dimensional (2D) modulation symbols selected from a double square 128 (DSQ128) constellation, which is a constrained constellation of 128 maximally spaced 2D symbols.